Soft Robotics

Unlike traditional robots, soft robots can conform and adapt to uncertain environments, interact with variable bodies, and enable safer human-robot interactions. However, soft materials lack the strength of rigid components. By employing granular materials in this field and controlling the unique ability of these granules to transition between compliant and rigid states via jamming, we are able to demonstrate shape change, adaptive navigation, and manipulation, thereby incorporating the properties of rigid and soft robots.

JAMoEBA (Jamming And Morphing Enabled Bot Array)

The JAMoEBA conceptualizes a soft robot comprised of a large number of 'hard' sub-robots that are loosely coupled and positioned on the outer surface of the system (or along its perimeter in 2D). The robotic subunits provide locomotion and morphing capabilities. The overall robot system can transition between flexible and rigid states by jamming the links between the subunits and/or its interior (if filled with passive particles representing a payload). This project is a close collaboration with the groups of Matthew Spenko and Ankit Srivastava at the Illinois Institute of Technology and Arvind Murugan at UChicago. Several JAMoEBA implementations are shown below.

A Boundary-Constrained Soft Swarm Robot with Vacuum Jamming

This is a soft boundary-constrained swarm, that displays compliant and configurable properties. The robot consists of a sealed flexible membrane that contains both a number of robotic subunits and passive granular material. The robot can also change the volume fraction of the sealed membrane by applying a vacuum, which gives the robot the ability to operate in two distinct states: compliant and jammed. The compliant state allows the robot to surround and conform to objects or pass through narrow corridors. Jamming allows the robot to form a desired shape; grasp, manipulate, and exert relatively high forces on external objects; and achieve relatively higher locomotion speeds. Locomotion is achieved with a combination of whegs (wheeled legs) and vibration motors that are located on the robotic subunits.

Cable-Driven Jamming of Boundary-Constrained Soft Robot

This JAMoEBA is a deformable robot comprising granular material in the interior and bounded by robotic subunits. The subunits are capable of locomotion with independently controlled differential drive and jamming via cable mechanisms connecting neighboring units. By actuating the cables we shorten the distance between the neighbors, reducing the internal volume and transitioning to a rigid state. In this jammed state we demonstrate directed locomotion with increased speed and accuracy. While in an unjammed state, the robot can adapt to the environment and conform around various objects which we aim to manipulate. Through simulations we study the scalability of this design and its effects on performance during various tasks, such as moving through narrow corridors.

K. Tanaka, Mohammad Amin Karimi, Bruno-Pier Busque, Declan Mulroy, Qiyuan Zhou, Richa Batra, Ankit Srivastava, Heinrich M. Jaeger and Matthew Spenko, "Cable-Driven Jamming of a Boundary Constrained Soft Robot," 2020 3rd IEEE International Conference on Soft Robotics (RoboSoft), New Haven, CT, USA, 2020, pp. 852-857.

A Universal Robotic Gripper Based on Jamming

Gripping and holding of objects are key tasks for robotic manipulators. The development of universal grippers able to pick up unfamiliar objects of widely varying shape and surface properties remains, however, challenging. Most current designs are based on the multi-fingered hand, but this approach introduces hardware and software complexities. These include large numbers of controllable joints, the need for force sensing if objects are to be handled securely without crushing them, and the computational overhead to decide how much stress each finger should apply and where.Here we demonstrate a completely different approach to a universal gripper. Individual fingers are replaced by a single mass of granular material that, when pressed onto a target object, flows around it and conforms to its shape. Upon application of a vacuum the granular material contracts and hardens quickly to pinch and hold the object without requiring sensory feedback. We find that volume changes of less than 0.5% suffice to grip objects reliably and hold them with forces exceeding many times their weight.We show that the operating principle is the ability of granular materials to transition between an unjammed, deformable state and a jammed state with solid-like rigidity. We delineate three separate mechanisms, friction, suction, and interlocking, that con-tribute to the gripping force. Using a simple model we relate each of them to the mechanical strength of the jammed state. This advance opens up new possibilities for the design of simple, yet highly adaptive systems that excel at fast gripping of complex objects.

Eric Brown, Nicholas Rodenberg, John Amend, Annan Mozeika, Erik Steltz, Mitchell R. Zakin, Hod Lipson, and Heinrich M. Jaeger, “Universal Robotic Gripper based on the Jamming of Granular Material”, Proc. Nat’l Acad. Sci. 107, 18809–18814 (2010). link to pdf file (incl. suppl. material), Cornell University press release
John R. Amend, Jr., Eric M. Brown, Nicholas Rodenberg, Heinrich M. Jaeger, and Hod Lipson, “A Positive Pressure Universal Gripper Based on the Jamming of Granular Material”, IEEE Transactions on Robotics 28, 341-350 (2012). pdf file

Jamming Skin Enabled Locomotion

A soft, mobile, morphing robot is a desirable platform for traversing rough terrain and navigating into small holes.In this work, a new paradigm in soft robots is presented that utilizes jamming of a granular medium. The concept of activators(as opposed to actuators) is presented to jam and unjam cells that then modulate the direction and amount of work done by a single central actuator. A prototype jamming soft robot utilizing JSEL (Jamming Skin Enabled Locomotion) with external power and control is discussed and both morphing results and mobility(rolling) results are presented. Future directions for the design of a soft, hole traversing robot are discussed, as is the role and promises of jamming as an enabling technology for soft robotics.

E. Steltz, A. Mozeika, N. Rodenberg, E. Brown, and H. M. Jaeger, "JSEL: Jamming Skin Enabled Locomotion," in Proc. IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 10-15 Oct. 2009; pp. 5672-5677 (2009). pdf file
E. Steltz, A. Mozeika, J. Rembisz, N. Corson, and H.M. Jaeger, Jamming as an Enabling Technology for Soft Robotics”, in Electroactive Polymer Actuators and Devices (EAPAD) 2010, ed. Yoseph Bar-Cohen, Proc. SPIE vol. 7642 (Conference on Smart Structures/NDE 2010, March 7-11, 2010, San Diego). pdf file